Trimming mechanisms for sewing machines



H. HACKLANDER 2,903,986

TRIMMING MECHANISMS FOR sswmc MACHINES Sept. 15, 1959 3 Sheets-Sheet '1 Filed March 25, 1957 IN V EN TOR.

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TR IMMING MECHANISMS FOR SEWING MACHINES Filed March 25. 1957 3 Sheets-Sheet 2 IN VEN TOR. Hans Hack/under Sept. 15, 1959 H. HACKLANDER mmmc MECHANISMS FOR sswmc MACHINES 3 Sheets-Sheet 3 Filed. Ila-rob. 25,. 1957 INVENTOR. Hans Hack/under Unite G NECHANISMS FOR SEWING MACHINES Application March 25, 1957, Serial No. 648,053

2 Claims. (Cl. 112-122) The present invention relates to sewing machines and specifically to a trimming mechanism for a sewing machine.

The primary object of this invention is to provide a new and improved trimming mechanism for a sewing machine, and particularly a trimming mechanism drive means which is simple and economical in construction, and is efficient, dependable and durable.

Having in mind the above and other objects that will be evident from an understanding of this disclosure, the invention comprises the devices, combinations and arrangements of parts as illustrated in the presently preferred embodiment of the invention which is hereinafter set forth in such detail as to enable those skilled in the art readily to understand the function, operation, construction and advantages of it when read in conjunction with the accompanying drawings in which:

Fig. 1 is a fragmentary view, partly in section and partly in elevation, of a sewing machine embodying the present invention.

Fig. 2 is a fragmentary head end elevational view of the sewing machine of Fig. 1 with the face plate removed.

Fig. 3 is a fragmentary horizontal sectional view on an enlarged scale of the head end of the bracket arm of the sewing machine of Fig. 1, but with the face plate removed.

Fig. 4 is a fragmentary sectional view taken substan tially on the line 4-4 of Fig. 1.

Fig. 5 is a detail view in section taken substantially on the line 5-5 of Fig. 1.

Fig. 6 is a fragmentary detail view in section taken substantially on the line 6--6 of Fig. 1.

Fig. 7 is a fragmentary sectional view taken substantially on the line 7--7 of Fig. 6.

The present invention is designed specifically for and is particularly useful in the sewing machine that forms the subject matter of applicants copending application Serial No. 609,836, filed September 14, 1956, to which reference should be had for a complete disclosure of the machine. The machine is herein disclosed only insofar as is believed to be necessary for an understanding of the present invention.

With reference to the drawings, the present invention is illustrated as embodied in a sewing machine having a frame including a bed 1, a standard 2 rising from one end of the bed 1 and a bracket arm 3 carried by the standard 2 and terminating in a head 4 overhanging the bed 1. The open top of the bracket arm 3 is closed by a cover plate 5 while the open end of the head 4 is closed by a face plate 6. The bed 1 is provided with a cloth plate 7 which at the point of stitch formation, has a throat plate 8, Figs. 2 and 4. Journaled longitudinally of the bed 1 is a main shaft 9 which extends through the wall of the bed adjacent to the standard to receive a belt pulley 10 by means of which power is delivered to the machine.

As fully disclosed in the above noted applicationSerial No. 609,836, in order to place thehead 4 adjacent to the front edge of the bed 1, or in other words, forwardly relaates Patent G ice tively to the standard 2 for the purpose of increasing the visibility at the point of stitch formation and facilitating reaching behind the head 4, the bracket arm 3 is angled forwardly relatively to the main shaft 9 or in other words relatively to the longitudinal axis of the bed 1. The illustrated machine is also designed to accommodate a number of different attachment mechanisms and for this purpose a pair of vertically spaced parallel attachment shafts (shown in phantom lines in 11a and 12a in Figs. 1 and 3) are designed to be journaled longitudinally of the bracket arm 3 in bearings fitted in bores 11 at the standard end of the bracket arm and bores 12 at the head end of the bracket arm. To simplify the driving relation between the main shaft 9 and the attachment shafts and between the attachment shafts and the mechanisms to be driven thereby, the attachment shafts and thus the bores 11 and 12 are on an axis parallel to the main shaft 9. Consequently, the attachment shafts are angled relatively to the longitudinal axis of the bracket arms 3 from the rear of the bracket arm adjacent to the head 4 to the front of the bracket arm adjacent to the standard 2.

The throat plate 8 is provided with feed dog slots 13, Fig. 4, through which a feed dog 14 operates to advance the work past the point of stitch formation, the feed dog 14 being mounted upon a feed bar 15. The work is held down against the throat plate 8 and feed dog 14 by a presser foot 16 mounted upon the lower end of a presser bar 17 which is mounted vertically in the head 4 for longitudinal sliding. The presser lifter mechanism, Figs. 1 and 3, includes a bell crank lever having a horizontal lever arm 13 connected by a link 19 and collar 20 to the presser bar 17 and a vertical lever arm 21 connected by a link 22 arranged longitudinally of the bracket arm 3 to the presser lifter actuating mechanism (not shown).

The stitching mechanism of the machine is also more fully disclosed in the above noted application Serial No. 609,836. Briefly, this mechanism includes a needle bar 23 mounted vertically in the head 4 for longitudinal reciprocation and having mounted upon the lower end thereof a pair of needles 24. Longitudinal reciprocation is imparted to the needle bar 23 by a rock lever 25 having a hub 26 intermediate its ends which is secured by a screw 26:: on a pivot shaft 27 pivotally mounted in the bracket arm 3. The rock lever 25 has a first lever arm 28 that is connected at its end by means of a link 29 and collar 30 to the needle bar 23 and a second lever arm 31 connected at its free end by means of a pitman 32 to a crank 33 on the main shaft 9. The hub 26 is arranged horizontally and is located vertically so that, when they are used, the attachment shaft 11a will pass over and the attachment shaft 12a will pass under the hub. Also, to provide clearance for the attachment shafts, the lever arms 28 and 31 are offset on the hub 26 so that the arm 28 is arranged in front and the arm 31 to the rear of the shafts. It is also necessary, in order to obtain a design that will be free from torsion and binding, that the ends of the arms 28 and 31 be on a line normal to the pivot axis of the rock lever 25. Thus the pivot shaft 27 is arranged normal to the longitudinal axis of the bracket arm 3, or in other words, is inclined to the axis of the main shaft by the complement of the angle of inclination of the bracket arm 3 relatively to the axis of the main shaft, and the lever arms 28 and 31 as they extend outwardly from the hub 26, are angled toward a common line that is normal to the pivotal axis of the rock lever.

As best seen in Figs. 1, 2, and 4, the illustrated trimmer mechanism includes a ledger blade 34 carried by a bracket 35 having a shank 36 that is seated in a groove 37 in the bed 1 and secured therein by a screw 38. The bracket 35 has a split strap end 39 in which is clamped, by a screw 40, a cylindrical element 41 having a through slot 42 that is rectangular in cross section. The ledger blade 34 cit- "tends: and in which it is secured by a screw 53,

tends through the slot 42' andis clamped against the one 'endthereof by ablock 43 positioned in the slot and forced toward the end by'a screw 44 threaded axially through the cylindrical element 41..

.The throat plate 8-is cutaway, at the inner-front corner thereof, as'at" 45, Fig.4, to provide for location of the cutting edge of the'ledger'blade 34 adjacent to the point oiistitch formation as defined by the innerone of the needles" 24';

bearing bushings 48. and 49 in the head 4. The trimmer blade 46 is secured to the trimmer bar 47 by means of a carrier 50 comprising a bodyportion 51 having a bore 52 into which the lowerendof the trimmer bar 47 ex- The carrier Whats a pair of spaced ears 54 and 55 having alinedbores in which is mounted for axial sliding movemom a plunger 56 having a split head 57 in which the trimmer blade 46 is secured by a screw 58. A collar 59 is secured on the plunger 56 between the ears 54 and 55 by a screw 60, and a coil compression spring 61 surrounds the plunger 56 between the ear 4 and the collar 59 to urge the plunger and the trimmer blade 46 carried thereby to the left in Figs. 1 and 4 and thus resiliently hold the. blade 46 laterally against the ledger blade 34. To

holdthe plunger 56 and'thus the trimmer blade 46 against cally arranged post 63'seated in a bore 64 in the bottom of the head 4 and having a flat 65 which is slidably engaged by a guide arm 66 on a collar 67 secured to the trimmer bar 47 by set screw'68.

Longitudinalreciprocation is imparted to the trimmer bar 47 by a connecting link 69 pivotally secured at its lower end to the collar 67 by a pivot pin 70 secured in the collar 67 by a set screw 71 and having the ends thereof journaledin bores in the bifurcated lower end of the link 69. At'its upper end, the link 69 is secured to a substantially horizontal lever arm 72 of a bell crank lever 73 by a pivot pin 74 secured in the end of the lever arm '72 by a set screw 75. and having the ends thereof journaledin bores in thebifurcated upper end of the link 69. The bell crank lever 73 has a hub 76 that is pivotally j mounted on a sleeve 77 secured to the inside of the front wall of the bracket arm 3 by a bolt 78 extending through the sleeve.77. The bolt 78 extends through a bore 79 in the front Wall of thebracket arm and is secured by a nut 80' threaded onto the inner end thereof. The bell crank lever 73 has a substantially vertical lever arm 81 having a pivot pin 82 secured therein by a set screw S3, the ends of the pin82 being journaled in bores in the bifurcated end of aconnecting rod 84. At its opposite end the rod 84 is formed with a strap 85 having a bore 86, Fig. 6, that loosely receives a sleeve 87 clamped on the reduced end 88 of a bolt 89 by a nut 90, a pair of washers or wear plates 91 being interposed between the sides of strap 85 and the opposed surfaces.

The bolt 89 has a shank 92 that extends through an elongated slot 93 in a depending crank arm 94 integral with the hub 26 of the rock lever 25, the shank 92 being generally of a diameter greater than the width of the slot 93 and having the opposite sides thereof slabbed as at 95, Fig. 7, to a dimension only slightly less than the width of the slotv 93. Thus, the bolt 89 is held against turning.

The stroke of the trimmer bar 47 can be adjusted by shiftingthe bolt 89 along the slot 93 which varies the connection point betweenthe crank arm 94 and rod 84 radially relatively to. the pivot axis of, the crank arm and thus varies the motion imparted to the, rod 84.

The. use of the, crank arm 94 on the hub 26 of the rock 1ever25 for, the trimmer drive provides an optimum con- 4 struction. As seen in Fig. 3, the drive connections for the trimmer bar 47, which comprises the crank arm 94, the connecting rod 84, the bell crank lever 73, and the link 69, all are on a line normal to the pivotal axis of the rock lever 25. Thus, there is obtained a direct drive relationship free from torsion and binding between the rock lever 25 and the trimmer bar 47. As above noted, the lever arm 28 of the rock lever 25 is connected to the front of the hub 26 in order to place that arm entirely in front of the attachment shafts 11a and 12a While the lever arm 31 is connected to the hub 26 and located entirely to the rear of the attachment shafts 11a and 12a. Thus, the lever arms 28 and 31 are free to rock without interfering with the attachment shafts which, to simplify the drive connections, are parallel to the axis of the main shaft 9. The lever arms 28 and 31 are also angled in order to place the free ends thereof on a line normal to the pivot axis of the rock lever 25. This angled relationship of the lever arm 28 also provide adequate clearance for the trimmer drive mechanism which originates on the hub 26 at substantially the same place as the lever arm 28, again to avoid interference with the attachment shafts, and then extends along a line normal to the pivot axis of the hub 26, thus diverging relatively to the lever arm 28. This construction provides for proper spacing of the trimmer bar 47 and needle bar 23 in the head 4 while, at the same time, providing for an optimum drive relationship for both the trimmer bar and needle bar, the drive mechanisms being free from interference with each other in a minimum of space and also being free from interference with the attachment shafts.

Consequently, the present invention comprises a unique trimmer mechanism which in itself provides an economical, dependable, durable and efiicient trimmer drive means, and which is particularly advantageous and useful when used in a sewing machine such as forms the subject matter of my copending application Serial No. 609,836.

Numerous alterations of the structure herein disclosed will suggest themselves to those skilled in the art. However, it is to be understood that the present disclosure relates to a preferred embodiment of my invention which is for purposes of illustration only and not to be construed as a limitation of the invention. All such modifications which do not depart from the spirit of the invention are intended to be included within the scope of the appended claims.

Having thus described the nature of the invention, what I claim herein is:

1. In a sewing machine having a frame including a bracket arm terminating in a head, stitch forming mechanism including a needle bar mounted in said head for longitudinal reciprocation, a rock lever having a hub intermediate its ends, a pivot shaft cooperating with said hub for pivotally mounting said rock lever in said bracket arm, means for operatively connecting said rock lever to said needle bar for imparting reciprocation to said needle bar upon oscillation of said rock lever, trimming mechanism comprising a trimmer bar mounted in said head for longitudinal reciprocation, a bell crank lever pivotally mounted in said bracket arm on an axis substantially parallel to the pivot axis of said rook lever, means connecting one lever arm of said bell crank lever to said trimmer bar to impart reciprocation to said trimmer bar upon oscillation of said bell crank lever, a crank arm integral with said rock lever and extending radially from said hub, a connecting rod connecting said crank arm to the other lever arm of said bell crank lever for imparting oscillation to said bell crank lever upon oscillation of said rock lever, and means for adjusting the point of connection between said connecting rod and crank arm radially relatively to the pivot axis of said crank arm to vary the movement imparted to said connecting rod.

2. In a sewing machine having a frame including a bed, a standard rising from one end Qf said bed, and a bracket arm carried by said standard and terminating in a head overhanging said bed, a main shaft journaled for rotation longitudinally of said bed, stitch forming mechanism including a needle bar mounted in said head for longitudinal reciprocation, a rock lever including a hub pivotally mounted intermediate its ends on a horizontal axis, and a pair of lever arms extending in opposite directions from laterally spaced points on said hub, said lever arms being angled with the free ends thereof disposed on a line normal to the pivot axis of said rock lever, means connecting the free end of a first one of said lever arms to said main shaft for imparting oscillation to said rock lever upon rotation of said main shaft and means connecting the free end of the second of said lever arm to said needle bar for imparting reciprocation to said needle bar upon oscillation of said rock lever, trimming mechanism comprising a trimmer bar mounted in said head for longitudinal reciprocation, a crank arm on said hub extending radially relatively to the pivot axis of said rock lever and arranged substantially in a plane normal to the pivot axis of said rock lever and including the axis of said trimmer bar, a bell crank lever pivotally mounted in said bracket arm on an axis substantially parallel to the pivot axis of said rock lever,

means connecting one lever arm of said bell crank lever to said trimmer bar to impart reciprocation to said trimmer bar upon oscillation of said bell crank lever, and means connecting said crank arm to the other arm of said bell crank lever for imparting oscillation to said bell crank lever upon oscillation of said rock lever, said trimmer bar, crank arm and bell crank lever being arranged generally in a plane normal to the pivotal axis of said rock lever.

References Cited in the file of this patent UNITED STATES PATENTS 314,710 Parker Mar. 31, 1885 1,410,860 Wohlpart Mar. 28, 1922 1,426,466 De Voe Aug. 22, 1922 1,566,810 Bates et a1. Dec. 22, 1925 1,675,696 Clayton July 3, 1928 1,737,395 Thompson et a1 Nov. 26, 1929 1,843,188 Zeier Feb. 2, 1932 2,322,397 Smith June 22, 1943 2,569,850 Falconer Oct. 2, 1951 2,729,179 Attwood Jan. 3, 1956 

